A novel type of T-T cell interaction removes the requirement for I-B region in the H-2 complex.
When tested in the in vitro T-cell proliferation assay, H-2a cells are nonresponders to lactate dehydrogenase B (LDH-B; L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) and to IgG2a myeloma protein. However, the cells can be converted into responders either by the addition to the culture of monoclonal anti-Ia.m7 antibody or by the removal from the culture of Lyt-2+ [T-lymphocyte-associated alloantigen (Lyt)-2 positive] lymphocytes. In both instances, the responsiveness can be suppressed again by the addition to the culture of monoclonal antibodies to I region-associated (Ia) molecules controlled by the I-A subregion. These data suggest that, in some H-2 haplotypes, the response to LDH-B and IgG2a is the result of interaction between the I-A and I-E subregions. The H-2a haplotype carries a responder allele at the I-A subregion but the responsiveness of H-2a cells is normally suppressed by T cells recognizing the antigen in the context of the I-E molecules. When the recognition of I-E molecules is blocked by an antiserum or when the cells capable of this recognition are removed, the H-2a cells become responders. These experiments demonstrate a nonresponder turned responder by antibody inhibition. They also demonstrate that the postulate of the I-B subregion is no longer necessary and provide additional evidence that the Ia molecules are the products of the immune response (Ir) genes.
D000818:Animals; D000954:Antigens, Surface; D002999:Clone Cells / Q000276:immunology; D005802:Genes, MHC Class II; D006183:H-2 Antigens / Q000235:genetics*; D000949:Histocompatibility Antigens Class II; D007156:Immunologic Memory; D007518:Isoantibodies; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008285:Major Histocompatibility Complex; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology*
D000954:Antigens, Surface; D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; D007518:Isoantibodies; C029805:Lyt antibodies